The United Nations mission in Liberia says it will respond strongly after threatening text messages were sent to the chief of the electoral commission.

National Elections Commission head Frances Johnson-Morris has told news organizations she laughed when she received two recent messages sent to her mobile phone.

But the U.N. mission in Liberia says it is taking the threats seriously, describing them as a serious impediment to the consolidation of peace and stability in Liberia.

The United Nations also says it will respond "robustly" to any threats of violence against individuals involved in the election process.

Liberians have been widely praised for holding peaceful and transparent elections on October 11, the nation's first post-war poll.

A presidential run-off vote is expected in November between the two top vote-getters, former football (soccer) star George Weah and former cabinet minister and World Bank economist Ellen Johnson-Sirleaf.